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| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2007-04-21 13:16:48 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2007-04-21 23:35:52 +0400 |
| commit | 4a56c1e41f19393577bdd5c774c289c199b7269d (patch) | |
| tree | a2c36198e3b4d78ccc8e373c3748112bc0645b0e /arch/arm/mm/ioremap.c | |
| parent | d5c98176ef34b8b78645646593c17e10f62f53ff (diff) | |
| download | linux-4a56c1e41f19393577bdd5c774c289c199b7269d.tar.xz | |
[ARM] mm 3: separate out supersection mappings, avoid for <4GB
Catalin Marinas at ARM Ltd says:
> The CPU architects in ARM intended supersections only as a way to map
> addresses >= 4GB. Supersections are not mandated by the architecture
> and there is no easy way to detect their hardware support at run-time
> (other than checking for a specific core). From the analysis done in
> ARM, there wasn't a clear performance gain by using supersections
> rather than sections (no significant improvement in the TLB misses).
Therefore, we should avoid using supersections unless there's a real
need (iow, we're mapping addresses >= 4GB).
This means that we can simplify create_mapping() a bit since we will
only use supersection mappings for addresses >= 4GB, which means that
the physical, virtual and length must be multiples of the supersection
mapping size.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/ioremap.c')
| -rw-r--r-- | arch/arm/mm/ioremap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index 0ac615c0f798..800855b2dc83 100644 --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -302,7 +302,7 @@ __ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size, #ifndef CONFIG_SMP if (DOMAIN_IO == 0 && (((cpu_architecture() >= CPU_ARCH_ARMv6) && (get_cr() & CR_XP)) || - cpu_is_xsc3()) && + cpu_is_xsc3()) && pfn >= 0x100000 && !((__pfn_to_phys(pfn) | size | addr) & ~SUPERSECTION_MASK)) { area->flags |= VM_ARM_SECTION_MAPPING; err = remap_area_supersections(addr, pfn, size, flags); |